The distributor type of fuel injection pump is well known. It feeds the injectors by pushing a pair of pumping plungers mounted in a transversely extending bore formed in the rotary distributor. The pumping plungers are actuated by shoes which are carried by rollers operated by the internal peripheral surface of a cam ring. The variation of the amount of fuel delivered to the engine is obtained by modifying through a throttle the flow area to the inlet port in the hydraulic head (see "The Theory, Calculation and Construction of Automotive Engines", B. Grunwald Bucharest, 1980).
A disadvantage of this pump is that the metering valve leads to delivery variations between injectors at partial loads and to irregular running of the engine. Another drawback is the fixed end of the injection cycle which leads to higher specific fuel consumption.
There is also known another rotary distributor fuel injection pump in which fuel injection is also effected by opposed pump plungers operated by an internal cam ring. Control of fuel delivery is obtained by modifying the travel of the plungers through hydraulically controlled axial movement of the distributor rotor. Since this rotar has a complex design it can be of to low reliability (GB 2,037,365 A).